1. Field of the Invention
The invention relates to the field of parachute recovery systems for aircraft and the like and, in particular, to a parachute recovery system for an ultra-miniature aircraft.
2. Description of Related Art
There are numerous obvious uses of parachutes: dropping of cargo from aircraft, landing spacecraft such as the Mercury, Gemini and Apollo spacecraft, braking systems for aircraft that are delayed after landing. The solid rocket motors on the space shuttle are lowered back down over the ocean using parachutes. In fact, parachutes have been used to lower aircraft to the ground. However, in all these vehicle applications, the parachute was internally stored within the vehicle. Most often drogue chutes were used to xe2x80x9cpullxe2x80x9d the main chute out into the air stream for deployment. Of course, on individuals and cargo dropped from aircraft, the parachute was externally mounted.
Scaling down these prior art systems for use on small micro-sized aircraft with wingspans of less than 15 inches has proven difficult, especially if they are to extremely compact and lightweight. In addition, providing a simple and reliable method of achieving release and deployment has also proven difficult, and the use of parachutes has been discounted. In fact, most such aircraft are recovered by making xe2x80x9cbellyxe2x80x9d landings, which typically damage the airframe and, if used, the propeller. Landing gear are typically not used because of the unacceptable complexity or weight penalty. Thus various arresting systems have been tried, such as butterfly or volleyball nets. However, aside from the damage that typically occurs, the main difficulty with these schemes is flying the aircraft into the net.
Thus it is a primary object of the invention to provide a parachute recovery system for an extremely small aircraft.
It is another primary object of the invention to provide a parachute recovery system for an extremely small aircraft that can be externally stored on the aircraft.
It is a further object of the invention to provide a parachute recovery system for an extremely small aircraft that is inexpensive to manufacture.
It is a still further object of the invention to provide a parachute recovery system for an extremely small aircraft that employees a reliable and simple method to achieve deployment.
The invention is a parachute system for a miniature aircraft, the aircraft having a front end, a rear end, a longitudinal axis, a center of gravity and an upper surface. In detail, the parachute system is mounted in a stored condition on the upper surface of the aircraft and includes a canopy having a stored condition and an expanded condition. Preferably, the canopy is hexagonal in shape and is vented at its center. A plurality of suspension lines having first ends connected to the periphery of the canopy in a spaced relationship and second ends coupled to an elastic member. Preferably, the elastic member is in the form of a ring. First and second risers are connected by their first ends to the upper surface of the aircraft between the front end and center of gravity on either side of the longitudinal axis and by their second ends to the elastic member. The first ends of the first and second risers are attached to the upper surface of the aircraft at a point that will cause the aircraft to descend with the longitudinal axis of the aircraft horizontal to the ground when the canopy is deployed.
With the aircraft center of gravity known and center of drag located between the center of gravity and the rear end thereof; the parachute is attached to the aircraft at a point located between the front end and the center of gravity. The distance from the center of gravity of the parachute attach point is such that when the canopy is in the expanded condition, the moment about the center of gravity caused by the drag of the canopy is equal to the drag of the aircraft, as the aircraft falls.
A restraint system is provided to releasably restrain the parachute assembly in the stored condition on the top surface of the aircraft and a release system to cause the restraint system to release the canopy from the stored condition. The restraint system preferably includes a retention cable or thread extending from the rear of the aircraft forward over the canopy, which loops under hooks mounted to the upper surface of the aircraft on either side of the longitudinal axis just ahead of the folded canopy of the parachute assembly. The ends of cable are attached to the release system includes an electrically actuated squib to which the ends of cable are tied directly thereto.
Thus after powered flight has termninated, actuation of squib will burn through, releasing the folded canopy. Aerodynamic forces will cause the canopy to fly off the rear end of the aircraft and inflate. After inflation, the canopy will slow the aircraft and essentially stops all forward motion. Note that the elastic ring will greatly reduce the shock load on the aircraft as the canopy inflates. The attachment location of the risers will cause the aircraft to descend vertically to the ground.